Short answer, they have no such rights. However they can always chance their arm with an application to the Department of Justice.
Long answer. The only categories of people who have a right to bring relatives to live with them are:
1 - Persons with refugee status, under international law
2 - EU citizens, under freedom of movement laws
3 - Some migrant workers, under domestic legislation
If any of the above become Irish citizens they lose those rights. Insane but true. Not sure it would have helped in your friend's case anyway because as a rule it's only spouses and minor children that can be brought in.